JPS5852856A - Method and device for sealing via consumable heater - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates generally to a sealing method and apparatus, and more particularly to:
The present invention relates to a method and apparatus for sealing a ceramic or metal lid to a ceramic package with a glass sealing material.

Many electronic circuits and components are exposed to the surrounding environment.
They are sealed and placed in a container in a roll that prevents them from being damaged. The sealing materials used in this case are (1) a metallic sealing material such as solder, (2) a ceramic sealing material containing various types of glass, and (c) an organic sealing material such as epoxy. Only two of these are the first to fulfill the true...methic seal.

This is because organic sealants can be penetrated by large amounts of material within O for a relatively short period of time (eg, a few days) compared to the lifetime of the circuit in which they are housed. If water vapor, for example, becomes permeable to the sealing material, it can chemically react with the ions contained in the back cage, such as chlorine, sodium and potassium, forming corrosion products that can attack wiring and/or electronic components. The failure of the nine circuits will be accelerated.

A number of metal alloys have been used as sealants with varying results. One of the highly desirable properties of metal sealants is their ability to withstand high temperatures. For example, common lead-tin solder provides a satisfactory seal at temperatures up to 125C. For example, for a temperature of 150C, 8
An alloy of 0% gold and 201% tin is preferred, but this is clearly more expensive. Unfortunately, the melting point of this alloy is approximately 280C, and melting of this material during the seal process can heat up electronic components, causing undesirable fluctuations in their parameters and premature failure of circuits. Sometimes it happens.

When using a glass sealant tube, its melting temperature is 40
Since the temperature is higher than 0C, equipment failure will be severe during circuit damage due to high sealing temperature.

Although glass sealants are significantly cheaper than the gold-tin alloys mentioned above, their high melting temperatures preclude their use where heating of the component is a problem.

A method of sealing a package without unduly heating the contents of the package has been developed, namely impulse or impact welding using fixed or rolling electrodes. These techniques require that the lid and package be metal, or at least require metal sealing surfaces on both the lid and the package. Unfortunately, the folding equipment used to perform such welding techniques is very expensive and requires specialized tools for each package size.

1 Hot-capping refers to a method of sealing a package with a metal or ceramic lid using a metal sealant. If either the lid or the package is ceramic, it must have a metal sealing surface fused to it, the seal being an electrically heated surface.
11. However, since the lid must be heated to at least the sealing temperature, the temperature of the electronic components or circuits will increase.

Since ceramic packages are cheaper than metal packages, and glassy seals are cheaper than metal-based seals, the most economical solution is to use a ceramic package and cover with a fused metallized seal. The purpose is to seal these with a glassy sealant without the need for layers.

It is an object of the present invention to provide an improved method and apparatus for sealing electronic circuits.

Yet another object of the present invention is to prevent excessive heating of electronic components or circuits within the device.

< Ceramic or metal i used on glass sealing material
It is an object of the present invention to provide a method and assembly for Hermedic sealing of an IT ceramic package.

Yet another object of the invention is achieved by providing a hermetically sealed ceramic or metal flt ceramic package without the need for a metal to ceramic sealing layer so that it becomes a permanent part of the seal. Ru. The above brefohm is connected with energy l[K,
Only enough heat is generated to form the sealed tube, and the total amount of heat generated is minimized. This will substantially reduce the temperature rise of the electronic components, depending on how external cooling techniques are used.

According to a broad feature of the invention, there is provided a heater preform disposed between a sealing surface of a package and a lid, the heater preform sealing to a package lid containing an electronic component when heated to a predetermined temperature; A heater preform is provided comprising a heater portion having a substantially corresponding area and shape and nine first and second contact portions connected to the heater portion.

According to another feature of the invention, there is provided a method for highly hermetically sealing a package containing an electronic component and having a sealing surface, the method comprising: and activating the heating element to create a sealing glass between the package and the lid.

According to another distinctive feature of the invention, there is provided a method of joining a fang 1 and a second ceramic body each having a sealing surface, the first and second bodies having a second ceramic body having a sealing surface. a glass coating having a coefficient of thermal expansion substantially equal to that of the first and second ceramic bodies, and a metal coating between the sealing surfaces of the first and second ceramic bodies; a heating element is arranged, the heating element being substantially conical thereto, and the heating element is actuated to melt the first and second bodies and the glass tube of the heating element, and melt the first and second bodies and the glass tube of the heating element; A method is provided for forming a seal with a second body such that the heating element becomes a permanent part of the shell seal.

I of the present invention! According to another feature, the apparatus forms a hermetic seal tube between the electronic component package and the lid by placing a seal preform in contact with the sealing surface of the electronic component package and the lid. a stage in which said package, 7'L/7, and a lid are arranged; a first means for applying pressure to said package, preform and lid in a direction compressing said preform; and said seal. An apparatus is provided comprising a second means for heating the preform to form the preform.

The above and other objects, features, and advantages of the present invention will be understood from the detailed description that follows, with reference to the accompanying drawings.

The present invention utilizes two types of heater preforms: single material preforms and composite preforms. The single-material heater preform is stamped or etched from metal (eg, copper) and shaped to fit the seal area of the package. The heater preform is shaped to most efficiently direct heat where it forms the seal. Since the temperature and heat power at any point on the preform vary inversely with respect to the cross-sectional area perpendicular to the direction of current flow, the temperature and heat power at a given point will narrow the preform at that given point. and by keeping its thickness constant. Of course, the same result can be achieved by making the heater preform thinner and maintaining a constant mid-tube.
It is preferable to maintain the thickness of the sealing area Kt) constant.

Figures 1a and 1b show the sealing part 10 and the ear 1.
FIG. 2 is a top view and a side view, respectively, of a composite heater preform consisting of two parts. As with single material heaters, a composite heater metal (eg, chrome, copper ring) is stamped or etched from a metal sheet approximately 0.005 inch thick. A sealing glass is applied to at least one side of the plate and preferably to both sides and the edges. The sealing glass, which is formulated to match the expansion of the metal, is fused to the metal to form a coating 14.

A coating is formed only on the rectangular seal portion 10.

No coating is formed on the ears 12. One convenient method of depositing on glass coatings involves dipping the cleaned large metal preform tube into a slurry of frit, drying, and fusing in an oven. The ears 12 serve as contact areas and are clamped to current-carrying terminals for passing heating current through the preform. Since the temperature increases as the width of the heater preform is reduced, the ears 12 remain relatively cool. The small holes 1, 6 at the entry and exit points of the rectangular heating area serve to create entry and exit areas that are slightly warmer relative to the rest of the reactor.

This compensates for cold spots that would otherwise be caused by heat flow from the rectangular seal area. If the metal from which the heater is made is thin enough and/or ductile enough, use a glass sealant whose coefficient of thermal expansion matches that of aluminum oxide to eliminate the difference in coefficient of thermal expansion with the metal. be able to.

Since fusing glass to metal is more difficult than fusing glass to glass, it is recommended to fuse the glass to the metal heater as a precursor. This ensures the integrity of the glass-to-metal bond. If a glassy coating is similarly applied to the sealing surface of the package and lid,
Ultimately...the mesh seal becomes glass to glass, which is easy to bond. By using a seal material formed with a coefficient of thermal expansion of 1 to match the metal heater and a glass having a coefficient of thermal expansion of 1 to match the material of the package and/or lid, a glass-to-glass seal can be created with a coefficient of expansion of 1. This tends to reduce the stress t-i''♀ that occurs when sealing different materials.Glass seals have an expansion coefficient t intermediate between that of the original glass and glass.Of course,
If the sealing material is not glassy, it is necessary to form a seal on all contact surfaces. It's fleeting.

In addition to stress relief, the glass layer on the lid and package tends to trap heat within the seal area. This is because glass is difficult to conduct heat through. This accelerates the sealing cycle and reduces the risk of package or twist damage due to thermal shock.

The glass layer on heater 10 also prevents the heater from overheating.

Figures 2a, 2b If % lr 2e and 2d are top, bottom, side and end views of a pancage 18 (e.g. aluminum oxide);
1 and 5b are bottom and end views of a ceramic lid 20 (eg, aluminum oxide). As is well known, package 18 is provided with a plurality of conductive leads 22 extending therefrom. package 1
8 and lid 200 both have a sealing glass layer 24t fused to their respective sealing areas, shown as black areas.
- have. The sealing glass is formulated to have a coefficient of thermal expansion that is compatible with the package and lid.

Oxidation 7 Minicum sealing glass is applied to the lid and package by silk screen or other convenient method, most conveniently the glass is fused in an oven. The thickness of the glass is approximately 0.015 inches (0.375 cm).

Figure 4 uses the heater preform of Figure 1: i! 2
1 of the device for sealing the lid and package in Figures and Figure 6
An example is shown. The packages 20 are arranged in nine tiers 26 with proper alignment and retainers 28. Step 26
are air or water cooled by supply and return lines 60 and 62, respectively. Heater 14 is placed over the sealing area of package 20C) and ears 12 rest on electrical terminal blocks 54 and 36, which conduct heating current through lines 38 and 40 when the circuit is completed. Ears 1112 are positioned on blocks 54 and 36 by holes 42 in ears 12 and projections 44 on blocks 64 and 66. Lid 18 is positioned such that its glassed area contacts the top surface of heater 14 . A predetermined amount of downward pressure is applied to 1118 by a metallic holder/heat sink 46 . Heat sink 46 also supply and return conduit 48
and 50 are air-cooled or water-cooled. The contact plunger 52 is then lowered into the ear 12 to ensure good electrical contact between the ear s12 and the terminal blocks 64 and 36. A heating current is then applied to the heater through the terminal blocks 34 and 36 and the ears 12 to form a glass seal.

If a hermetically sealed device does not pass a leak test, it is usually very difficult to remove the lid without thermally or mechanically damaging the contents of the package.

Using the above process, removal of the lid is made relatively simple. That is, if the heater 14 is reheated, the sealing material will be softened and the lid will be removed. If necessary, the package is resealed with a new lid and heater tube. Of course, the lid removal process is simple if the heating ears or tabs 12 have not already been removed.
2 is removed, the lid is removed using a specially designed contact electrode. I! In addition, in the case of defects due to seal leakage, it is sufficient to reheat the sealant and reflow the sealant.

It will be apparent that the process described above is easily adapted to mechanized or automated processes. The heater preform is formed as a continuous strip or roll and is automatically fed to the sealing area. The package and lid are also transported automatically and electrical contact is made by hydraulically, pneumatically or electrically actuated plungers.

In summary, a process tube has been described above that seals over a package and lid using a heater device or brefohm tube that is applied directly to the seal area and becomes an integral part of the seal. This process may include certain types of soldering, welding, adhesion, or gluing based on the type of sealant used. On the rounding to begin the sealing process,
Heat is applied to fuse glassy or metallic materials together, or to cure organic adhesives such as epoxies. Heat is generated from the heater device KwLt (from an external power source).
(b) generating a current tS in the heater device by electric induction; (C) dielectric heating using a suitable dielectric material in the sealing region; or (d) obtaining the sealing temperature by thermal conduction. This is generated by applying a heat tube to the protruding tab. In the case of dielectric heating, the preform may or may not be an adhesive material and need not be electrically conductive. The material of the heater device (excluding its coating) may be -) a metal such as copper, chromium, aluminium, porcelain, steel, etc. or a vitreous material such as glass, vitreous enamel or other ceramics. or (e) a conductive coating such as a ceramic coating or a thick film ink.

If electrical connections are required to the heater preform, removable protruding tabs or ears are provided.

A special contact probe may be used to current tube the heater, in which case no protruding tabs or ears are required. In the case of induction heating or dielectric heating, contact means are not required.

If electrical heating is desired, a power source is provided to provide a moderate current at each time during a given time interval. The maximum temperature that the electronic components within the package may be exposed to [
The current shape is selected to optimize the sealing process tube, taking into account Although the power supply for current heating is simple, the power supplies currently used for induction heating or dielectric heating are not complicated either.

If a metallic seal is desired, three types of seals are formed. First, a high temperature seal is formed using the heater only to provide heat to melt and weld together the sealing areas of the fIK, package, lid, and possibly the heater itself. To do this most efficiently, the resistance of the heater must be small compared to the resistance of the package and lid. A variation of this solution involves fusing the ceramic by co-firing the tungsten. A tungsten heater coated with a low melting point metal or alloy can be used.

A second type of metal seal involves the use of a single metal heater device or preform.

In this case, the heater female is actually the top solder preform,
Once this is melted, the adjacent sealing surfaces, which have been made suitable for soldering operations by prior tinning, plating or other methods, are bonded. Care must be taken to avoid melting the tabs or ears (when using electrical heating) as the sealing surface is adjacent to a heat absorbing object.

Third, the metal heater is coated with, for example, a tin-lead alloy or perhaps an alloy with <80% AV and 201GSn. If the heater is made of highly conductive material (e.g. steel, aluminum, etc.), most of the heat will be transferred to the heater.
The remainder is generated into solder. This method will be most effective if the metallic seal am is fused to the non-conductive package and lid.

The above explanation is just an example. It will be apparent to those skilled in the art that various changes in form and detail may be made therein without departing from the scope of the invention as defined in the claims.

[Brief explanation of drawings]

2a, 2b, 2c and 2d are top views of a package for electronic components or circuits, respectively; Figures 3a and 6b are bottom views, end views, and end views of the lids to be sealed to the packages of Figures 2a, f2b, 2C, and 2d, respectively. Figure 4 shows how the heater preforms of Figures 1a and 1b are used to fit the packages of Figures 2a, 2b, 2c, and 2d into the packages of Figures 3a and 3b.
FIG. 2 is an exploded view of one embodiment of the lid-sealing device shown in FIG. 10...Seal part 12...Ear-like part 14...
・Coating 16... Hole 18... Package 20... Lid 22... Lead 24.
・・Seal glass 26・・Step 28・・
・Alignment and holding tool 54.56...Electrical terminal block

Claims (1)

[Claims] 1. In a heater preform for sealing a package containing electronic components to a lid, the preform is heated to a predetermined temperature by being placed between the sealing surface of the preform tube package and the lid; The preform is characterized in that it has a heater part having an area and shape substantially corresponding to the sealing surface, and first and second contact parts connected to the heater part and the second contact part. form. 2. Scope of Request for 411FF111 In a method for hermetically sealing a package containing an electronic component to a lid using the heater preform described in item 1, a sealing surface between the heater preform and the package and the lid is provided. and heating the heater preform to form a seal at the interface between the package and the lid. 3. A heater preform tube according to claim IB 1 is used to create a knee gap between an electronic component package and its lid.
- an apparatus for forming a mesh seal, comprising: a stage in which said package, preform and lid are arranged; first means for applying pressure to said package, preform and lid in a direction compressing said preform; and forming said seal. and second means for heating the preform so as to heat the preform.